The Knowledge Engineering Review The Knowledge Engineering Review, Vol. 10:2, 1995 The Knowledge Engineering Review, Vol. 10:2, 1995, 115 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence ( DAI The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) ( Steeb et al. The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped ( Maes The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al. The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing ( ABC The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 ( Houlder The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994 The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994). The Knowledge Engineering Review, Vol. 10:2, 1995, 115-152 Intelligent agents: theory and practice MICHAEL WOOLDRIDGE1 and NICHOLAS R. JENNINGS2 1 Department of Computing Manchester Metropolitan University Chester Street, Manchester MI 5GD, UK (M. Wooldridge@doc.mmu.ac.uk) Department of Electronic F.ngineering, Queen Mary & Westfield College, Mile End Road, London El 4N.S, UK ( N. R.Jennings@gm w.ac.uk) Abstract The concept of an agent has become important in both artificial intelligence (AI) and mainstream computer science. Our aim in this paper is to point the reader at what we perceive to be the most important theoretical and practical issues associated with the design and construction of intelligent agents. For convenience, we divide these issues into three areas (though as the reader will see, the divisions arc at times somewhat arbitrary). Agent theory is concerned with the question of what an agent is, and the use of mathematical formalisms for representing and reasoning about the properties of agents. Agent architectures can he thought of as software engineering models of agents; researchers in this area are primarily concerned with the problem of designing software or hardware systems that will satisfy the properties specified by agent theorists. Finally, agent languages are software systems for programming and experimenting with agents; these languages may embody principles proposed by theorists. The paper is not intended to serve as a tutorial introduction to all the issues mentioned; we hope instead simply to identify the most important issues, and point to work that elaborates on them. The article includes a short review of current and potential applications of agent technology. 1 Introduction We begin our article with descriptions of three events that occur sometime in the future: I. The key air-traffic control systems in the country of Ruritania suddenly fail, due to freak weather conditions. Fortunately, computerised air-traffic control systems in neighbouring countries negotiate between themselves to track and deal with all affected flights, and the potentially disastrous situation passes without major incident. 2. Upon logging in to your computer, you are presented with a list of email messages, sorted into order of importance by your personal digital assistant (PDA). You are then presented with a similar list of news articles; the assistant draws your attention to one particular article, which describes hitherto unknown work that is very close to your own. After an electronic discussion with a number of other PD As, your PDA has already obtained a relevant technical report for you from an FTPsite, in the anticipation that it will be of interest. 3. You are editing a file, when your PDA requests your attention: an email message has arrived, that containsnotification about a paper you sent to an important conference, and the PDA correctly predicted that you would want to sec it as soon as possible. The paper has been accepted, and without prompting, the PDA begins to look into travel arrangements, by consulting a number of databases and other networked information sources. A short time later, you are presented with a summary of the cheapest and most convenient travel options. We shall not claim that computer systems of the sophistication indicated in these scenarios are just around the corner, but serious academic research is underway into similar applications: air-traffic M. WOOLDRIDGE AND NICHOLAS JENNINGS 116 control has long been a research domain in distributed artificial intelligence (DAI) (Steeb et al., 1988); various types of information manager, that filter and obtain information on behalf of their users, have been prototyped (Maes, 1994a); and systems such as those that appear in the third scenario are discussed in (Mc Gregor, 1992; Levy ct al., 1994). The key computer-based com ponents that appear in each of the above scenarios are known as agents. It is interesting to note that one way of defining Al is by saying that it is the subfield of computer science which aims to construct agents that exhibit aspectsof intelligent behaviour. The notion of an "agent" is thus central to AI. It is perhaps surprising, therefore, that until the mid to late 1980s, researchers from mainstream AI gave relatively little consideration to the issues surrounding agent synthesis. Since then, however, there has been an intense flowering of interest in the subject: agents are now widely discussed by researchers in mainstream computer science, as well as those working in data communications and concurrent systems research, robotics, and user interface design. A British national daily paper recently predicted that: "Agent-hased computing (ABC) is likely to be the next significant breakthrough in software development.·· (Sargent, 1992) Moreover, the UK-based consultancy firm Ovum has predicted that the agent technology industry would be worth some US$3.5 billion worldwide by the year 2000 (Houlder, 1994).